Laminoplasty implant, method and instrumentation

ABSTRACT

In one embodiment, the present invention is a system for use in a laminoplasty procedure, the system including an implant comprising a first body and a second body, the first and second bodies adapted to slide relative to one another; and an implantation instrument including: a shaft having a longitudinal length, a proximal end, a distal end and a hollow throughbore along at least a portion of its length; a handle positioned on the proximal end of the shaft; an actuator rod having a proximal portion and a distal portion, the actuator rod being positioned within the hollow throughbore of the shaft; a knob adapted to engage the proximal portion of the actuator rod; a first connector adapted to engage the distal portion of the actuator rod; and a second connector fixedly secured to the distal end of the shaft.

BACKGROUND OF THE INVENTION

Spinal stenosis is a narrowing of the spinal canal, through which thespinal cord passes, that causes compression of the spinal cord. Such anarrowing can be caused by numerous factors including bone spurs,degeneration of the intervertebral disks and facet joints, andthickening of the ligaments. Among the symptoms spinal stenosis canproduce are pain and/or numbness in the arms, clumsiness of the hands,and gait disturbances.

One such procedure for the repair of spinal stenosis is called alaminoplasty, in which the targeted vertebra is cut such that thevertebra can be spread apart to increase the diameter of the spinalcanal. The cut produces two lamina ends, between which a laminoplastyplate is positioned to bridge the gap formed in the vertebra. Normally,a plate of an appropriate size is selected, bent to the desired shapeand then fastened to the vertebra utilizing a plurality of screw holespositioned on the plate.

Two different laminoplasty procedures are in current use. The first iscalled the unilateral or “open door” laminoplasty in which one lamina(positioned to one side of the spinous process) is cut all the waythrough, while the other lamina (on the opposite side of the spinousprocess) is cut only partially through to create a hinge. The vertebralportion, including the spinous process, is then rotated about the hinge,and the plate is secured within the opening, maintaining the opening ofthe spinal canal.

The second procedure is called the bilateral or “French door”laminoplasty in which the midline of the spinous process is cutlengthwise all the way through, and each of the lamina are cut partiallythrough to form two hinges. The bisected spinous process is then spreadapart, and a plate is secured within the opening, again increasing thediameter of the spinal canal. Such laminoplasty procedures relievepressure on the spinal cord while maintaining the stabilizing effects ofthe posterior elements of the vertebrae. By relieving pressure on thespinal cord it is the goal of laminoplasty to stop the progression ofdamage to the spinal cord and allow for a degree of recovery offunction.

Commonly in “open door” laminoplasty procedures, the laminoplasty plateis of a solid construction having a rigid length to which the laminaends must be positioned relative thereto. Alternatively the plate of anappropriate size is selected and bent to the desired shape andpreferably has a plurality of screw holes, but again, such a plate has arigid length. Adjustable length plates are also known in the art, thoughthey are cumbersome and difficult to implant as they include multiplemoving parts, all of which must be handled by a surgeon. Also, theaccompanying instrumentation with such plates includes multiple handleswhich decrease the precision with which a surgeon can operate.

BRIEF SUMMARY OF THE INVENTION

Thus, there is a need in the art for an adjustable plate that can beeasily expanded and include accompanying instrumentation which is simpleto use and can perform the surgery by requiring minimal actions by thesurgeon.

In one embodiment of the claimed invention, a laminal implant includes afirst body and a second body, the first and second bodies beingremoveably coupled to one another and slidable relative to one anothersuch that the implant may be expandable. The implant may further includea flange on an end of both the first and second bodies for engagementwith first and second lamina ends of the vertebra. The implant may alsoinclude a tab on the first body and a plurality of teeth on the secondbody, wherein the tab and teeth may interact to allow unidirectionalsliding of the first body relative to the second body. The teeth may beshaped such that they may pass the tab when moving in a first direction,but may be stopped from moving, by the tab, in a second directionopposite the first direction. The implant may further include at leastone throughhole on each of the first and second bodies, adjacent theflanges, through which a fastener may be positioned to secure theimplant to the lamina ends. The first and second bodies may also includea receiving channel on one of the bodies which may receive at least aportion of the body, such as a slide portion, therein. The receivingchannel and slide interaction may form a track along which the first andsecond bodies may slide but still remain in proper alignment to oneanother.

In another embodiment, the present invention may include a laminalimplant including a first body including a first flange adapted toengage a first lamina end, a tab and a receiving channel; and a secondbody including a second flange adapted to engage a second lamina end,and a plurality of teeth adapted to engage the tab, at least a portionof the second body adapted to be positioned within the receivingchannel. The first and second bodies are adapted to slideably engage oneanother to expand or compress the implant. The first and second bodiesmay both also include an at least one through hole, through which afastener may be positioned to provide further engagement, in addition tothe flanges, to the lamina ends. Further, at least a portion of theflange of the first body may be pliable. The implant may further includeat least one pin hole on each of the first and second bodies capable ofinteracting with an insertion instrument. Moreover, the first and secondflanges may be adapted to engage at least two sides of each of thelamina ends. Additionally, the flange of the first body may be adaptedto engage three sides of the first lamina end.

In a further embodiment, the present invention is a system for use in alaminoplasty procedure, the system including: an implant comprising afirst body and a second body, the first and second bodies adapted toslide relative to one another to expand the implant; and an implantationinstrument including: a shaft having a longitudinal length, a proximalend, a distal end and a hollow throughbore along at least a portion ofits length; a handle positioned on the proximal end of the shaft; anactuator rod having a proximal portion and a distal portion, theactuator rod being positioned within the hollow throughbore of theshaft; a knob adapted to engage the proximal portion of the actuatorrod; a first connector adapted to engage the distal portion of theactuator rod; and a second connector fixedly secured to the distal endof the shaft, wherein one of the first or second connectors is adaptedto be removeably coupled to one of the first or second bodies, and theother of the first or second connectors is adapted to be removeablycoupled to the other of the first or second bodies, wherein actuation ofthe knob slides at least one of the first or second bodies relative tothe other.

Furthering this embodiment, the knob may be positioned adjacent to andproximal of the handle, and also the knob may be fixedly secured in alongitudinal position relative to the handle, but may be freelyrotatable relative to the handle. The knob and actuator rod may also becoupled together through a threaded connection, such that the actuatorrod is adapted to move longitudinally through the shaft by actuation ofthe knob. The first connector may also be adapted to actuate by thelongitudinal movement of the actuator rod. For example, the firstconnector may include a slot within which may be positioned a tabextending from the actuator rod, wherein the tab may be adapted totravel within the slot by the longitudinal travel of the actuator rod.Moreover, the first connector may be pivotally connected to the shaftsuch that as the tab travels within the slot, the first connector pivotsrelative to the shaft, wherein the first connector may be adapted topivot from an initial position substantially parallel to the secondconnector to a plurality of subsequent positions angled from the secondconnector. Furthermore, the first and second connectors each may includean attachment tip to removeably couple to a pin hole on each of thefirst and second bodies. The coupling of the attachment tip and pin holemay be a friction fit. Further, the actuator rod may be coaxial with theshaft. The first connector may also be actuable, through the actuatorrod, by the knob.

In another embodiment of the claimed invention, an instrument for usewith an implant in a laminoplasty procedure may include a handle, shaft,trigger and first and second jaws, the shaft extending from the handle,the trigger positioned adjacent to the handle, and the first and secondjaws extending from the shaft opposite the handle, wherein one of thefirst or second jaws is capable of being removeably coupled to one of afirst or second bodies of the implant, and the other of the first orsecond jaws is capable of being removeably coupled to the other of thefirst or second bodies, wherein actuation of the trigger moves the firstand second jaws relative to one another, and thus, the first and secondbodies of the implant relative to one another. The instrument mayinclude a linkage between the first and second jaws such that rotationalmovement of the trigger may be translated into movement of the jaws suchthat the jaws remain parallel as they move relative to one another.

In a further embodiment, the present invention may include a method ofperforming a laminoplasty, the method including: removeably coupling animplant and an instrument, the implant comprising a first body and asecond body, a flange on the first body and a flange on the second body,the first and second bodies being slidable relative to one another toexpand the implant; advancing the implant to the laminoplasty site whichincludes first and second lamina ends; engaging one cut end with theflange of the first body and engaging the other cut end with the flangeof the second body; expanding the implant using the instrument;decoupling the instrument from the implant; and fixedly securing theimplant to the first and second lamina ends. The implant may be fixedlysecured to the lamina ends through further engagement of the first andsecond flanges to the lamina ends through the placement of at least onefastener through each of the first and second bodies and into the laminaends.

Alternatively, prior to the step of expanding the implant, fixedlysecuring the implant to one of the first or second lamina ends. Again,the implant may be fixedly secured to one of the lamina ends throughfurther engagement of the first or second flange to the lamina endthrough the placement of at least one fastener through the first orsecond body and into the lamina end. In this embodiment, the implant mayalso be secured to the other lamina end subsequent to the step ofdecoupling the instrument from the implant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first embodiment of an implant including a firstbody and a second body.

FIGS. 2-4 illustrate close-up views of various details of the implant ofFIG. 1.

FIG. 5 illustrates another embodiment of an implant including a firstbody and a second body.

FIGS. 6 a and 6 b illustrate various views of the second body of theimplant of FIG. 5.

FIGS. 7 a-7 c illustrate various views of the first body of the implantof FIG. 5.

FIGS. 8-9 illustrate one embodiment of an instrument of the presentinvention, and FIG. 9 also includes the implant of FIGS. 1-4 removeablycoupled thereto.

FIGS. 10 a and 10 b illustrate another embodiment of an instrument ofthe present invention to which an implant of the present invention maybe removeably coupled thereto.

FIGS. 11 a and 11 b illustrate yet another embodiment of an instrumentof the present invention, also including the implant of FIGS. 5-7removeably coupled thereto.

FIG. 12 illustrates one embodiment of the positioning of an implant ofthe present invention between lamina ends during the performance of alaminoplasty procedure.

DETAILED DESCRIPTION

The various embodiments of the present invention which will be discussedbelow will be discussed as if used in an “open door” laminoplasty (e.g.,as in FIG. 12). However, the present invention is not intended to belimited to such a procedure as it is envisioned that the followingimplants, instrumentation, systems and methods may be used on othertypes of laminoplasty procedures and other spinal surgeries.

In a first embodiment, illustrated in FIGS. 1-4, the present inventionincludes an implant 10 including a first body 20 and a second body 30.The first and second bodies 20,30 each have a length, and the first andsecond bodies are removeably coupled to one another and slidablerelative to one another, along their lengths, to expand or compress theimplant.

The first body 20 includes a flange, such as for example a U-shapedsaddle 25 as in FIG. 1, which engages up to three sides of one laminarcut end of the vertebra (e.g., outer side surface, inner side surface,and the cut edge surface). While the flange is sufficient to engage theimplant with the laminar cut end, the flange may also include at leastone through hole 23, through which a fastener (for example, see fastener134 in FIG. 11 b) may be passed to further engage the flange to thelaminar cut end in a fashion to fixedly secure the implant to the laminaend. Suitable fasteners may be a bone screw, tack, pin, or othersuitable structure commonly used in the spine. The flange may alsoinclude an opening 26, which results in the saddle 25 having lessmaterial than if saddle 25 were completely solid. The minimized materialallows for the saddle 25 to have greater pliability. For example, thesurgeon may be able to adjust the shape of the saddle 25, by bending thesaddle or the like, to provide for a better fit onto the lamina end.Moreover, the opening 26 may optionally provide a location for placementof a bone graft or other osteogenic material, therethrough. The opening26 may provide a window through which bone growth may occur, as well asserve to secure the bone graft in place while such bone growth takesplace.

The second body 30 also includes a flange, such as for example ashoulder 32 as in FIG. 1, which is sized to engage up to two sides ofthe other lamina end of the vertebra (e.g., outer side surface and cutedge surface). While the flange is sufficient to engage the implant withthe lamina end, the flange may also include at least one through hole33, through which a fastener (for example, see fastener 134 in FIG. 11b) may be passed to further engage the flange to the lamina end in afashion to fixedly secure the implant to the lamina end.

The first and second bodies 20,30 are slidable relative to one another,and thus each includes a structure to allow such a sliding arrangement.For example, as illustrated in FIGS. 1-4, the bodies may include areceiving channel 27 and an at least a portion of the other body adaptedto be positioned within the channel 27, such as slide 37. Of course, thechannel and slide could be transposed such that the channel is on thesecond body and the slide is on the first body; and likewise the firstbody could slide within the second body instead of the second bodysliding within the first body, as illustrated.

The first and second bodies 20,30 further include cooperating structureswhich may secure the first and second bodies relative to one another toinhibit or otherwise control the sliding action. For example, asillustrated in FIGS. 1-4, the first body 20 includes a structure, alongat least a portion of its length, for interacting with the second bodysuch as, for example, a tab 21. The second body includes a structurewhich interacts with the structure on the first body (e.g., tab 21),such as for example a plurality of teeth 31. The tab 21 and teeth 31 mayinteract to allow unidirectional sliding of the first body relative tothe second body. The teeth 31 may be shaped such that they may pass thetab when moving in a first direction, but may be prohibited from moving,by the tab 21, in a second direction opposite the first direction. Forexample, the tab 21 may be biased such that the tab 21 is resting at thebase of the teeth. As a tooth passes under the tab, the tab deflectsoutwardly as an inclined face of the tooth passes under the tab, whichallows the tooth to pass, but, the tab then returns to its originalposition once the tooth clears the tab. Of course, the tab will notdeflect if the tooth attempts to pass the tab in the opposite directionsince the shape of the tooth is inclined at an angle on only one side,and is generally perpendicular on the other side. A detailed view ofsuch an arrangement is illustrated in FIG. 2.

Thus, for example, as will be discussed further below, the first andsecond bodies may slide away from one another to expand the length ofthe implant and thus expand the distance between the two lamina ends,and consequently, enlarge the diameter of the spinal canal. But, thisarrangement prevents compression of the length of the implant, suchthat, once implanted and expanded to the desired length, the implantwill maintain such length, and thus such expansion of the spinal canal.Tab 21 may be lifted or deflected manually by for example placing anappropriate instrument in access port 28, which would clear the tab fromthe teeth 31 and thus allow the first and second bodies to movebi-directionally since the teeth/tab interaction would no longer limitmovement to only a single sliding direction. Lifting the tab may, usingthe embodiment illustrated, thus allow the first and second bodies tomove towards one another and compress the length of the implant. Thismay be useful in the event of unintentional expansion of the implantprior to surgery, such that the surgeon can simply return the implant toits compressed position, using standard surgical instrumentation, inpreparation for implantation into the spine. Alternatively, this mayalso be useful in the event of unintentional overexpansion of theimplant once already implanted into the cut lamina.

The implant may further include a stop 22 which prevents the first andsecond bodies from being pulled completely apart. The stop 22 may beuseful, for example, in preventing the surgeon from unintentionallypulling apart the implant in the midst of surgery, which would delay thesurgery and cause an inconvenience to the surgeon. While the stop 22 isshown in one position, for example in FIG. 4, the stop may be positionedelsewhere on the implant so long as it substantially prevents the firstand second bodies from being pulled apart (e.g., as in stop 122 in FIG.6 a).

Optionally, a bone graft or other bone-growth promoting (osteogenic)material may be positioned along at least a portion of the length ofimplant 10. For example, a bone graft may be placed through opening 26and positioned along the length of the implant such that, over time,bone growth may occur from at least one of the lamina ends and throughthe bone graft. The opening 26 may stabilize the bone graft, while alsoallowing for uninhibited growth of bone through the opening 26 andbetween the lamina ends.

In another embodiment, the implant of the present invention may include,as illustrated in FIGS. 5-7, an implant 110 having a first portion 120and a second portion 130. Implant 110 is similar in many respects toimplant 10, and as such similar reference numbers (e.g., 20 vs. 120)refer to similar structures, except for certain differences, such as thefollowing examples. First, implant 110 may further include pin holes129,139 for interaction with an instrument (such as those describedbelow) such that the instrument may engage and removeably couple theimplant thereto. Second, body 130 may include two through holes 133a,133 b for the placement of a second fastener (for example, see FIG. 11b) therethrough. Third, stop 122 may be positioned on body 130 ratherthan body 120.

While this embodiment includes pin holes 129,139 for interaction withthe implantation instrument, other such interactive elements may beused. For example, as to the implant illustrated in FIG. 1, theinstrument may have a forked grasping tip, or the like, which may beused to interact with the implant.

The implantation instrument of the present invention may be used forimplantation of the implant, including at least holding, placement,expansion and release of the implant between lamina ends within a cutlamina of a spine.

In one embodiment, illustrated in FIGS. 8 a, 8 b and 9, the presentinvention includes an implantation instrument 50 which includes a shaft55 extending between a handle 70 at a proximal end and a distal end 80.The instrument further includes an actuation mechanism which allows thesurgeon to manipulate the distal end 80. As illustrated in the exemplaryembodiment of FIGS. 8 a, 8 b and 9, the actuation mechanism may includea trigger 60 and actuator rod 65. In this embodiment, the rotationalmovement of trigger 60, when depressed or released by the surgeon'sfinger, is translated into linear longitudinal movement of actuator rod65, which then imparts this movement onto the distal end 80. The handle70 may also include a trigger guard 61 to assist in preventingunintentional actuation of the trigger. The actuator rod 65 may furtherinclude a ratchet mechanism which may provide improved control ofmovement as well as provide an ability of the surgeon to maintain adesired position.

Continuing with this embodiment, the distal end 80 may include first andsecond jaws 82,83, each having an attachment tip 84 for connection toimplant 10 (as in FIG. 9). The jaws 82,83 may be connected to oneanother through a linkage 81, which is in turn connected to the shaftvia a connecting link 86 and to actuator rod 65 via banana link 85. Sucha series of connections may cause the jaws 82,83, through actuation ofthe trigger 60, to move towards or away from one another, andconsequently, when the implant 10 is secured to the instrument 50, tocause the first and second bodies 20,30 to slide relative to oneanother. As illustrated, the distal end 80 is positioned at an anglerelative to the shaft 55. This angle may be any desired angle, and mayeven be about 0 degrees such that the distal end is substantially linearto the shaft. This angle as illustrated, though, may provide improveduse by the surgeon in providing a better angle of entry and line ofsight to the surgical space, as well as provide better transfer of forcefrom the trigger, to the actuator rod, to the distal end.

This movement of the jaws 82,83, as to this embodiment, is obtained asfollows. Trigger 60 may have a default or biased position, though such aposition is not required. If a biased positioned is included, typicallya spring or other mechanism may be included to tension the triggertowards one position. In FIG. 8 a, for example, the trigger 60 may betensioned in the forward position, such that the default or biasedposition places the jaws 82,83 close together (and thus, if implant 10is attached to the jaws, the implant would be in a default compressedconfiguration, as in FIG. 9). Biasing the trigger in this fashion mayalso provide for some resistance on the trigger when the surgeondepresses it, which may provide added control for the surgeon. Thisbiasing also improves the ability of the instrument to hold the implant10 due to the compression of the implant between the jaws.

As the trigger 60 is depressed, or pulled rearwards towards the handle70, the trigger pivots and forces the actuator rod 65 forwards, towardsthe distal end 80. This forward motion places a forward force on thebanana link 85. However, the linkage 81 is held in place relative to theshaft 55 by connecting link 86. Thus, as shown in FIG. 8 b, the forwardmotion of the actuating rod 65 causes the banana link 85 to rotate andexpand linkage 81, since the linkage 81 is prohibited from movingforward. As the linkage 81 expands, the jaws 82,83 move apart and expandthe space between them. However, due to the connecting link and linkageinteraction, the jaws do not change orientation relative to one another(they remain substantially parallel to one another) or move laterallycloser or farther from the rest of the instrument. Thus, as will bediscussed further below, the linkage configuration may allow the surgeonto place the implant 10 in position on the vertebra and then expand theimplant 10, while keeping it in position on the vertebra. The surgeondoes not have to account for additional movement of the implant as thetrigger is depressed, such as rotational movement, lateral movement, orthe like, because the linkage configuration translates depression of thetrigger into unidirectional expansion of the implant.

The instrument 50 can act as a holder of the implant, as illustrated inFIG. 9. The trigger 60 may be spring biased in a closed position toprovide better securement of the implant 10. The instrument can also actas an expander for the implant in conjunction with holding the implant.Of course, when an implant is connected to the jaws, and the implant isexpanded when positioned on and between two lamina ends, the instrumentwill perform both an expansion of the implant and, consequently, anexpansion of the space between the two lamina ends as well as anexpansion of the spinal canal.

In a further embodiment, as illustrated again in FIG. 9, the presentinvention includes a system including an implant 10 and an instrument50. The implant 10 is expandable or compressible and includes a firstbody 20 and a second body 30, the first and second bodies being slidablerelative to one another to expand or compress the implant. Theinstrument 50 includes a handle 70, shaft 55, trigger 60 and first andsecond jaws 82,83, the shaft extending from the handle, the triggerpositioned adjacent to the handle, and the first and second jawspositioned on the shaft opposite the handle, wherein one of the first orsecond jaws is capable of being removeably coupled to one of the firstor second bodies 20,30, and the other of the first or second jaws iscapable of being removeably coupled to the other of the first or secondbodies 20,30, wherein actuation of the trigger moves the first andsecond jaws relative to one another. As the jaws move relative to oneanother, the first and second bodies of the implant may also slidablymove relative to one another. The implant 10 is press-fit, or otherwiseremovably connected, to the jaws 82,83 on attachment tips 84.

FIGS. 10 a and 10 b illustrate a further embodiment of an implantationinstrument 150. In this embodiment, instrument 150 includes a shaft 155having a length and proximal and distal ends. Shaft 155 is also hollowalong at least a portion of its length to accommodate an actuator rod165 therethrough. In the illustrative example, the shaft 155 is hollowalong its entire length. The instrument 150 also includes a handle 170positioned along the proximal portion of the shaft 155. The handle andshaft may be fixedly secured to one another or, alternatively, thehandle and the shaft may be manufactured as a single, monolithicstructure.

The actuator rod 165 has a proximal portion and a distal portion, and aknob 160 is adapted to engage the proximal portion of the actuator rod.Knob 160, as illustrated, may be positioned adjacent to and proximallyof the handle 170. Knob 160 may also be fixedly secured in alongitudinal position relative to the handle 170, but may be freelyrotatable relative to the handle. This freedom of rotation permits theactuation of knob 160, through rotation around the longitudinal lengthof the instrument, and thereby cause linear or longitudinal movement ofthe actuator rod 165 through the shaft 155, as the actuator rod 165 andshaft 155 may be coaxial with one another. The translation of rotationalmotion of the knob 160 to longitudinal movement of the actuator rod 165may be accomplished through the coupling of the two elements by athreaded connection 168. As will be discussed below, actuation of theknob slides at least one of the first or second bodies 120,130 ofimplant 110 relative to the other.

The instrument 150 also includes a first connector 183 and a secondconnector 182, wherein one of the first or second connectors is adaptedto be removeably coupled to one of the first or second bodies 120,130,and the other of the first or second connectors is adapted to beremoveably coupled to the other of the first or second bodies 120,130.As illustrated, the first connector 183 is adapted to engage the distalportion of the actuator rod 165, while the second connector 182 isfixedly secured to the distal end of the shaft 155.

The first connector 183 may be adapted to actuate by the longitudinalmovement of the actuator rod 165 created by the actuation of knob 160.For example, as illustrated in this embodiment, the first connector 183may include a slot 187 within which may be positioned a tab 162extending from the actuator rod 165, wherein the tab 162 may be adaptedto travel within the slot 187 as coordinated by the longitudinal travelof the actuator rod 165 through the shaft. Moreover, the first connector183 may be pivotally connected to the shaft 155 such that as the tab 162travels within the slot 187, the first connector pivots relative to theshaft, wherein the first connector may be adapted to pivot from aninitial position substantially parallel to the second connector 183 (asin FIGS. 10 a, 10 b) to a plurality of subsequent positions angled fromthe second connector. This pivot may occur around pivot pin 163 whichextends from and is fixedly secured with shaft 155.

The second connector 182 is fixedly secured to the shaft 155, and assuch the first or second body 120,130, whichever is removeably coupledto the second connector 182, is also held in place relative to the shaft155. Thus, in use, as the first connector 183 pivots, as explainedabove, the first or second body 120,130 removeably coupled to firstconnector 183 will likewise move with first connector 183 and sliderelative to the other body 120,130 removeably coupled to the secondconnector 182.

Each of the first and second connectors may include an attachment tip184 to removeably couple to a pin hole 129,139 on each of the first andsecond bodies 120,130. The coupling of each attachment tip and pin holemay be a friction fit or the like.

This embodiment of the implantation instrument 150 may also be combinedwith an implant, such as implant 110, to form a system includinginstrument 150 and at least one implant 110. The system, for use in alaminoplasty procedure, includes an implant 110 comprising a first body120 and a second body 130, the first and second bodies adapted to sliderelative to one another to expand or compress the implant, and animplantation instrument 150 including: a shaft 155 having a longitudinallength, a proximal end, a distal end and a hollow throughbore along atleast a portion of its length; a handle 170 positioned on the proximalend of the shaft; an actuator rod 165 having a proximal portion and adistal portion, the actuator rod 165 being positioned within the hollowthroughbore of the shaft 155; a knob 160 adapted to engage the proximalportion of the actuator rod; a first connector 183 adapted to engage thedistal portion of the actuator rod; and a second connector 182 fixedlysecured to the distal end of the shaft, wherein one of the first orsecond connectors is adapted to be removeably coupled to one of thefirst or second bodies, and the other of the first or second connectorsis adapted to be removeably coupled to the other of the first or secondbodies, wherein actuation of the knob slides at least one of the firstor second bodies relative to the other.

Furthering this embodiment, the knob 160 may be positioned adjacent toand proximal of the handle 170, and also the knob 160 may be fixedlysecured in a longitudinal position relative to the handle 170, but maybe freely rotatable relative to the handle. The knob 170 and actuatorrod 165 may also be coupled together through a threaded connection 168,such that the actuator rod is adapted to move longitudinally through theshaft by actuation of the knob. The actuator rod 165 may be coaxial tothe shaft 155. The first connector 183 may also be adapted to actuate bythe longitudinal movement of the actuator rod, via the actuation of theknob 160. In one embodiment, the first connector may include a slot 187within which may be positioned a tab 162 extending from the actuatorrod, wherein the tab may be adapted to travel within the slot by thelongitudinal travel of the actuator rod. Moreover, the first connectormay be pivotally connected to the shaft, at pivot pin 163 extending fromthe shaft, such that as the tab travels within the slot, the firstconnector pivots relative to the shaft, wherein the first connector maybe adapted to pivot from an initial position substantially parallel tothe second connector to a plurality of subsequent positions angled fromthe second connector. Furthermore, the first and second connectors eachmay include an attachment tip 184 to removeably couple to a pin hole129,139 on each of the first and second bodies. The coupling of theattachment tip and pin hole may be a friction fit.

In use, the system is capable to adjusting the implant 110 from, forexample, a compressed position (as in FIG. 5) to an expanded position(as implant 10 is presented in FIG. 1) through the actuation of the knob160. Thus, in this embodiment, once the implant was in place and engagedto the lamina ends (discussed below), a surgeon may, holding the handle170 substantially steady to minimize or prevent its rotation, rotate theknob 160 which thereby rotates the knob relative to the actuator rod 165at threaded connection 168. The rotation of the knob forces the actuatorrod 165 to move longitudinally which, in this embodiment, would bedistally, towards the first connector 183. The actuator rod 165 movesdistally as a result of the threaded connection 168 because the actuatorrod may be inhibited from rotating along with the knob, by for examplepin 162 or by another similar structure, such that the threading of theknob instead travels along the thread of the actuator rod. As theactuator rod 165 moves distally, tab 162 also moves distally, therebyforcing the portion of the first connector including the slot 187 alsodistally. As the first connector is affixed by pivot pin 163, the distalmotion of the slot 187 causes generally proximal movement of the otherend of the first connector 183, which includes the attachment tip 184.Thus, as the attachment tip 184 of the first connector 183 movesproximally, it moves away from the attachment tip 184 of the secondconnector 182, thereby increasing the distance between the twoconnectors. Of course, since the implant 110 is removeably coupled tothe first and second connectors, the first and second bodies 120,130 ofthe implant also slide apart, thereby expanding the implant. Since theimplant is positioned and engaged to the lamina ends, the expansion ofthe implant also expands the spinal canal and the distance between thelamina ends.

FIGS. 11 a and 11 b illustrate yet another embodiment of the presentinvention, namely, an instrument 250 including a shaft 255 having alongitudinal length, a proximal end, a distal end and a hollowthroughbore along at least a portion of its length. The hollowthroughbore accommodates an actuator rod 265 therethrough. In theillustrations, the shaft 255 is hollow along its entire length. Theinstrument also includes a handle 270 positioned along the proximalportion of the shaft 255. The handle and shaft may be fixedly secured toone another or, alternatively, the handle and the shaft may bemanufactured as a single, monolithic structure.

The actuator rod 265 has a proximal portion and a distal portion, and aknob 260 is adapted to fixedly engage the proximal portion of theactuator rod. Knob 160, as illustrated, may be positioned proximally ofthe handle 170. The knob 160 and actuator rod 265, being fixedly engagedthereto, are freely rotatable relative to the handle 270 and shaft 255.The actuator rod 265 and shaft/handle may be coaxial and further coupledtogether via a threaded connection 268. This freedom of rotation permitsthe actuation of knob 260, through rotation around the longitudinallength of the instrument, and thereby causes linear or longitudinalmovement of the actuator rod 265 relative to and through the shaft 255.Thus, the threaded connection 268 accomplishes the translation ofrotational movement of the knob and actuator rod into longitudinalmovement relative to the shaft 255. As will be discussed below,actuation of the knob slides at least one of the first or second bodies120,130 of implant 110 relative to the other.

The instrument 250 also includes a first connector 283 and a secondconnector 282, wherein one of the first or second connectors is adaptedto be removeably coupled to one of the first or second bodies 120,130,and the other of the first or second connectors is adapted to beremoveably coupled to the other of the first or second bodies 120,130.As illustrated, the first connector 283 is adapted to engage the distalportion of the actuator rod 265, while the second connector 282 isfixedly secured to the distal end of the shaft 255.

The first connector 283 may be adapted to actuate by the longitudinalmovement of the actuator rod 265 created by the actuation of knob 260.For example, as illustrated in this embodiment, the first connector 283may include a bore 287 within which a tab 262, extending from actuatorrod 265, may be rotatably coupled, such that as the actuator rod 265rotates and moves longitudinally (and distally), the tab 262 freelyrotates within bore 287 while imparting longitudinal force on the firstconnector 283 to move the first connector distally. The first connectormay be prevented from rotating by pin 263, which prevents rotation ofthe first connector while still allowing the longitudinal movement ofthe first connector caused by the actuator rod 265.

The second connector 282 is fixedly secured to the shaft 255, and assuch the first or second body 120,130 which is removeably coupled to thesecond connector 282 is also held in place relative to the shaft 255.Thus, in use, as the first connector 283 moves distally, as explainedabove, the first or second body 120,130 removeably coupled thereto willslide relative to the body 120,130 removeably coupled to the secondconnector 282.

Each of the first and second connectors may include an attachment tip284 to removeably couple to a pin hole 129,139 on each of the first andsecond bodies 120,130. The coupling of each attachment tip and pin holemay be a friction fit.

As illustrated in FIGS. 11 a and 11 b, this embodiment of theimplantation instrument 250 may also be combined with an implant, suchas implant 110, to form a system including instrument 250 and at leastone implant 110. In use, the system is capable to adjusting the implant110 from, for example, a compressed position (as in FIG. 11 b) to anexpanded position (as implant 10 is presented in FIG. 1) through theactuation of the knob 260. Thus, in this embodiment, once the implantwas in place and engaged to the lamina ends (discussed below), a surgeonmay, holding the handle 270 substantially steady to prevent itsrotation, rotate the knob 260 which thereby rotates the actuator rod 265relative to the shaft 255 at threaded connection 268. The rotation ofthe knob forces the actuator rod 265 to rotate and move longitudinally(on account of the threaded connection 268) which, in this embodiment,would be distally, towards the first connector 283. The actuator rod 265moves distally as a result of the threaded connection 268 because theactuator rod rotates relative to the shaft and handle while the shaftand handle are prevented from rotating by the surgeon (e.g., by holdingthe handle). As the actuator rod 265 moves distally, tab 262 also movesdistally, thereby forcing the first connector also distally. As thefirst connector is affixed by pin 263, tab 262 rotates freely withinbore 287, and thus the first connector does not rotate along with tab262. The first connector does move distally, though, along withattachment tip 284. As first connector and attachment tip 284 movedistally, they move away from the second connector 282 and attachmenttip 284 of the second connector, such that the distance between the twoconnectors, and two attachment tips, increases. Of course, since theimplant 110 is removeably coupled to the first and second connectors,the first and second bodies 120,130 of the implant also slide apart,thereby expanding the implant. Since the implant is positioned andengaged to the lamina ends, the expansion of the implant also expandsthe spinal canal and the distance between the lamina ends.

In another alternative embodiment, the present invention may include akit including one of the above instruments and a plurality of implantswhich may be used on multiple vertebrae in a single patient or inmultiple patients in subsequent surgeries. Alternatively, the kit mayinclude implants of various dimensions and sizes such that the surgeonmay select the properly sized implant for the specific patient and typeof vertebra. Then, the implant may be expanded, from a compressedconfiguration, to fine tune the implant length for the specificapplication.

The various implants, instruments, systems and kits of the presentinvention may be sterilized and packaged from the manufacturer as acombined system, such that the system can be removed from the packagingand immediately used in a surgery. Alternatively, the system may includean individually packaged implant and an instrument which may be sold andpackaged separately. Additionally, the various instruments may besterilizable and reusable in subsequent surgeries.

The various disclosed embodiments of the implant and instrument of thepresent invention may be used in various methods of surgery. While it isenvisioned that any of the instruments may be used with the implantembodiments disclosed, the below discussion of exemplary methods willuse the implant of FIGS. 5-7 and the instrument of FIGS. 10 a and 10 bfor illustrative purposes.

In one embodiment, the method of performing a laminoplasty includesremoveably coupling an implant and an instrument, the implant includinga first body and a second body, a flange on the first body and a flangeon the second body, the first and second bodies being slidable relativeto one another to expand or compress the implant. For example, this stepmay include removeably coupling implant 110 to instrument 150, byattaching attachment tips 184 to pin holes 129,139, with the implant 110in a substantially compressed configuration, such that the first andsecond connectors 183,182 may be generally parallel to one another.Next, the implant is advanced to the laminoplasty site which includesfirst and second lamina ends, as illustrated, for example, in FIG. 12.The implant is then positioned to engage one cut end with the flange ofthe first body and engaging the other cut end with the flange of thesecond body, and expanding the implant using the instrument. The implantis then decoupled from the instrument. At this point, the implant may besubstantially secured within the lamina. However, to ensure the implantremains in place and in a proper orientation relative to the vertebra,the implant may be fixedly secured to the lamina ends through furtherengagement of the first and second flanges to the lamina ends throughthe placement of at least one fastener through each of the first andsecond bodies and into the lamina ends.

In another embodiment of the present invention, the method of performinga laminoplasty may be similar to the above method however, prior to thestep of expanding the implant, the implant is fixedly secured to one ofthe lamina ends using a fastener (such as fastener 134 of FIG. 11 b).For example, a fastener may be placed through at least one ofthroughbores 123, 133 a or 133 b, after the flanges of the first andsecond bodies have engaged the lamina ends. The implant may then beexpanded, as necessary, using the instrument. The implant is thendecoupled from the instrument. Finally, additional fasteners are appliedin the other through bores of the implant (e.g., through bores 123 andthe other of 133 a or 133 b) to fixedly secure the implant to the firstand second lamina ends.

In yet a further embodiment, a method of the present invention mayinclude steps similar to those above, however, the instrument 150, forexample, may be coupled to the implant after the implant is in place onthe lamina ends. In this embodiment, alternative instrumentation may beused to place the implant onto the lamina ends. For example, a pair offorceps or the like may be used to move the implant into position. Asecond instrument, such as a grasper or the like may pry the cut ends ofthe lamina apart. Once the lamina ends are expanded, the forceps areused to move the implant into position onto the lamina ends. The grasperand forceps are then withdrawn from the surgical site and instrument 150is then secured to the implant, along with at least one fastener tofurther secure the implant to at least one of the lamina ends. Themethod then continues as discussed above.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. A system for use in a laminoplastyprocedure, the system comprising: an implant comprising a first body anda second body, the first and second bodies adapted to slide relative toone another to expand or compress the implant; and an implantationinstrument comprising: a shaft having a longitudinal length, a proximalend, a distal end and a hollow throughbore along at least a portion ofits length; a handle positioned on the proximal end of the shaft; anactuator rod having a proximal portion and a distal portion, theactuator rod being positioned within the hollow throughbore of theshaft; a knob adapted to engage the proximal portion of the actuatorrod; a first connector adapted to engage the distal portion of theactuator rod; and a second connector fixedly secured to the distal endof the shaft, wherein one of the first or second connectors is adaptedto be removeably coupled to one of the first or second bodies, and theother of the first or second connectors is adapted to be removeablycoupled to the other of the first or second bodies, wherein actuation ofthe knob slides at least one of the first or second bodies relative tothe other.
 2. The system of claim 1, wherein the knob is positionedadjacent to and proximal of the handle.
 3. The system of claim 2,wherein the knob is fixedly secured in a longitudinal position relativeto the handle, but is freely rotatable relative to the handle.
 4. Thesystem of claim 3, wherein the knob and actuator rod are coupledtogether through a threaded connection.
 5. The system of claim 4,wherein the actuator rod is adapted to move longitudinally through theshaft by actuation of the knob.
 6. The system of claim 5, wherein thefirst connector is adapted to actuate by the longitudinal movement ofthe actuator rod.
 7. The system of claim 6, wherein the first connectorcomprises a slot within which is positioned a tab extending from theactuator rod.
 8. The system of claim 7, wherein the tab is adapted totravel within the slot by the longitudinal travel of the actuator rod.9. The system of claim 8, wherein the first connector is pivotallyconnected to the shaft such that as the tab travels within the slot, thefirst connector pivots relative to the shaft.
 10. The system of claim 9,wherein the first connector is adapted to pivot from an initial positionsubstantially parallel to the second connector to a plurality ofsubsequent positions angled from the second connector.
 11. The system ofclaim 10, wherein the first and second connectors each include anattachment tip to removably couple to a pin hole on each of the firstand second bodies.
 12. The system of claim 11, wherein the coupling ofthe attachment tip and pin hole is a friction fit.
 13. The system ofclaim 1, wherein the actuator rod is coaxial with the shaft.
 14. Thesystem of claim 1, wherein the first connector is actuable, through theactuator rod, by the knob.